builders. One more scapular supporting muscle, the pectoral is minor, also takes origin from the front side of the chest, but this one inserts on the acromion of the scapula (fig. 8.11), and from that position pulls it forward.
The rhomboids and the levator scapulae stabilize the scapulae posteriorly. The rhomboid muscles adduct the scapula, pulling its medial border toward the midline from its origin on the thoracic spine (fig. 8.12), and the levator scapulae elevates the scapula, as its name implies, pulling on its upper border (fig. 8.12) from an origin on the transverse processes of C1-4.
The most superficial muscle that supports the scapula is the trapezius, so-named because the two trapezius muscles viewed together from the rear form a trapezoid (fig. 8.10). Each muscle is flat and triangular-shaped, takes origin medially from a line that runs from the skull to T12, and inserts on the clavicle and the spine of the scapula, the hard bony ridge you can feel on your upper back (fig. 8.10). Depending on which fibers of the muscle are active, the trapezius exerts traction to pull the scapula up, down, medially, or all three at the same time.
These five muscles not only stabilize the scapula, making a dependable foundation for movements of the arms, they move the scapula around on the surface of the back. The scapula can be moved laterally (the serratus anterior) and medially (the rhomboids); it can be elevated (the levator scapulae) or depressed (the lower fibers of the trapezius); and its pointed lower angle can be rotated out and upward (the trapezius and serratus anterior) or in and downward (the rhomboids, pectoralis minor, and levator scapulae). All of these movements are crucial to inverted postures and to the exercises that prepare us for them.
To check for yourself how the scapula works, ask someone who is slender, lightly muscled, and flexible to stand with their arms hanging alongside their thighs. Then trace the borders of both scapulae visually and by feel. The medial borders for each of these triangular bones are parallel to one another, an inch or so to either side of the midline, and the lateral borders angle up and laterally. The prominent bony landmark on lop is the scapular spine. Next, while feeling the inferior angle of each scapula (its lowermost tip), ask your subject to slowly lift both hands overhead. Notice that as the arms are lifted each scapula rotates on an axis that runs roughly through the middle of the scapular spine, and from that axis you can feel that the inferior angle is carried in an arc out and up. This is called upward rotation. If this movement is constrained it will be harder to do the headstand, not to mention any other posture requiring an overhead stretch. Now ask your subject to lower both arms, spread the tops of the shoulders, and at the same time pull the inferior angles of the scapulae toward the midline of the body. This is the opposite movement—rotation of the inferior angle of the scapula down and medially, or downward rotation.
Other movements are self-explanatory. Still feeling the scapulae, a your subject to do shoulder rotations. Watching carefully, notice that lifti g the shoulders elevates the scapulae, pulling the shoulders downwa i depresses them, pulling the shoulders to the rear adducts them, a. d pulling the shoulders forward abducts them.
THE PECTORALIS MAJOR AND LATISSIMUS DORS!
Although most of the muscles that act on the arm take origin from e scapula and insert on the humerus, there are two mayor exceptions— e pectoralis major and the latissimus dorsi—both of which bypass ie scapula on their way to insert on the humerus. The pectoralis majo is the largest muscle that takes origin from the front of the chest (f s. 8.8-9). If you press your left hand against the side of your head with ie arm angled out to the side, brace your left elbow with your right h; d, and try to pull your left elbow forward and to the right, the pector lis major tendon will tighten just above the axilla as it passes lateralis to insert on the humerus. Its most powerful action is to pull the . m forward from behind, as when you try to do a push-up with the hii ds spread out laterally from the chest.
The latissimus dorsi takes a broad origin from the lower thoracic nd lumbar spine, the sacrum, and the crest of the ilium (fig. 8.10), and f m there it courses around the chest wall just lateral to the scapula ig. 8.9), runs through the axilla, and inserts on the front of the hume us. It's unique—the only muscle in the body that connects the lower nd upper extremities; its most powerful action is extension—pulling he arm down from above as in swimming, or lifting the body in a chi up (chapter 1).
Was this article helpful?
This powerful tool will provide you with everything you need to know to be a success and finally achieve your dream of shedding the tummy fat and reveal your six pack abs. Making weight loss promises to yourself is easy but making them stick is something else which requires much more than just some words and thoughts. In the quest to make weight loss resolutions that eventually see some level of success there needs to be some careful planning and thought exercised beforehand.